Thin films of ZnO have been deposited on glass and silicon substrates by the pulsed laser deposition technique employing a KrF laser (λ=248 nm). The influence of the deposition parameters, such as substrate temperature, oxygen pressure, and laser fluence on the properties of the grown films, has been studied. All the films grown over a rather wide range of deposition conditions were found to be optically transparent, electrically conductive, and c-axis oriented, with the full width at half-maximum (FWHM) of the (002) x-ray reflection line being very often less than 0.25°. Under optimized laser fluence and oxygen pressure conditions, highly c-axis oriented films having a FWHM value less than 0.15° and optical transmittance around 85% in the visible region of the spectrum have been grown at a substrate temperature of only 350 °C. These are among the best properties yet reported for ZnO films grown by any technique at such a low temperature.

Ba 0.5 Sr 0.5 TiO 3 ͑BST͒ thin films grown on Si by an in situ ultraviolet-assisted pulsed laser deposition ͑UVPLD͒ technique exhibited significantly higher dielectric constant and refractive index values and lower leakage current densities than films grown by conventional PLD under similar conditions. X-ray photoelectron spectroscopy ͑XPS͒ investigations have shown that the surface layer of the grown films contained, besides the usual BST perovskite phase, an additional phase with Ba atoms in a different chemical state. PLD grown films always exhibited larger amounts of this phase, which was homogeneously mixed with the BST phase up to several nm depth, while UVPLD grown films exhibited a much thinner ͑ϳ1 nm͒ and continuous layer. The relative fraction of this phase was not correlated with the amount of C atoms present on the surface. Fourier transform infrared spectroscopy did not find any BaCO 3 contamination layer, which was believed to be related to this new phase. X-ray diffraction measurement showed that although PLD grown films contained less oxygen atoms, the lattice parameter was closer to the bulk value than that of UVPLD grown films. After 4 keV Ar ion sputtering for 6 min, XPS analysis revealed a small suboxide Ba peak for the PLD grown films. This finding indicates that the average Ba-O bonds are weaker in these films, likely due to the presence of oxygen vacancies. It is suggested here that this new Ba phase corresponds to a relaxed BST surface layer.

We have studied the structural properties of ZnO thin films grown on Al2O3 (00.1) single-crystal substrates by pulsed-laser deposition using either a femtosecond or a nanosecond laser. Although hexagonal ZnO films deposited on sapphire substrate were epitaxially grown in both cases, the crystalline quality was found to be very different: ZnO films grown with the femtosecond laser are characterized by a higher mosaicity, a smaller crystallite size, a larger content of defects but also smaller residual stresses than ZnO films obtained by nanosecond laser ablation. These differences can be explained according to the kinetic energy of the species evolved during laser ablation as deduced from plasma characterization with a charged-coupled device camera: close to 1 KeV in the femtosecond regime for the population species emitted from the target with the highest velocity, versus a few hundreds of eV in the case of nanosecond pulses. The high energy species irradiation associated with a femtosecond laser is likely to induce a large structural disorder together with stress relaxation during ZnO films growth.

Hydrogen-free diamond-like carbon ͑DLC͒ films have been deposited with a 100 fs ͑FWHM͒ Ti:sapphire laser beam at intensities I in the 10 14-10 15 W/cm 2 range. The films were studied with scanning probe microscopy, variable angle spectroscopic ellipsometry, Raman spectroscopy, and electron energy loss spectroscopy. DLC films with good scratch resistance, excellent chemical inertness, and high optical transparency in the visible and near infrared range were deposited at room temperature. As the laser intensity was increased from 3ϫ10 14 to 6ϫ10 15 W/cm 2 , the films showed an increased surface particle density, a decreased optical transparency (85%˜60%), and Tauc band gap (1.4˜0.8 eV), as well as a lower sp 3 content (60%˜50%). The time-of-flight spectra recorded from the laser plume exhibited a double-peak distribution, with a high energy suprathermal ion peak preceding a slower thermal component. The most probable ion kinetic energy showed an I 0.55 dependence, increasing from 300 to 2000 eV, when the laser intensity was varied from 3ϫ10 14 to 6ϫ10 15 W/cm 2 , while the kinetic energy of suprathermal ions increased from 3 to over 20 keV and showed an I 0.33 dependence. These high energy ions are believed to have originated from an electrostatic acceleration field established by suprathermal electrons which were formed by resonant absorption of the intense laser beams.

High-performance amorphous (α−) InGaZnO-based thin film transistors (TFTs) were fabricated on flexible polyethylene terephthalate substrates coated with indium oxide (In2O3) films. The InGaZnO films were deposited by rf magnetron sputtering with the presence of O2 at room temperature. The n-type carrier concentration of InGaZnO film was ∼2×1017 cm−3. The bottom-gate-type TFTs with SiO2 or SiNx gate dielectric operated in enhancement mode with good electrical characteristics: saturation mobility 11.5 cm2 V−1 s−1 for SiO2 and 12.1 cm2 V−1 s−1 for SiNx gate dielectrics and drain current on-to-off ratio >105. TFTs with SiNx gate dielectric exhibited better performance than those with SiO2. This is attributed to the relatively high dielectric constant (i.e., high-k material) of SiNx. After more than 500 h aging time at room temperature, the saturation mobility of the TFTs with SiO2 gate dielectric was comparable to the as-fabricated value and the threshold voltage shift was 150 mV.